Pyrotechnic time delay compositions composed of boron carbide, sodium periodate, and polytetrafluoroethylene have been developed for use in the U.S. Army hand-held signal. The new compositions were developed to replace the currently used composition that contains potassium perchlorate and barium chromate, chemicals that are facing increasing regulatory scrutiny. Static tests in aluminum hand-held signal delay housings demonstrated a wide range of available inverse burning rates (1.3−20.8 s/cm), which includes the 7−8.5 s/cm range required for hand-held signals. The roles of loading pressure, mixture stoichiometry, and component particle size are described herein.
Friendly green giant: A pyrotechnic with green‐light emission for both military use and civilian fireworks has been developed without the need to use barium or chlorinated compounds. Boron carbide serves as a green colorant and fuel in the presence of potassium nitrate oxidizer and an epoxy binder. This environmentally friendly formulation is very stable to impact, friction, and electrostatic discharge, and has a high thermal stability.
The development of a red, chlorine-free pyrotechnic illuminant of high luminosity and spectral purity was investigated. Red-light emission based solely on transient SrOH(g) has been achieved by using either 5-amino-1H-tetrazole or hexamine to deoxidize the combustion flame of a Mg/Sr(NO3 )2 /Epon-binder composition and reduce the amount of both condensed and gaseous SrO, which emits undesirable orange-red light. The new formulations were found to possess high thermal onset temperatures. Avoiding chlorine in these formulations eliminates the risk of the formation of PCBs, PCDDs, and PCDFs. This finding, hence, will have a great impact on both military pyrotechnics and commercial firework sectors.
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